<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <p>总数：{{ total }}</p>
        <my-component v-model="total"></my-component>
    </div>
    <script src="https://unpkg.com/vue/dist/vue.min.js"></script> 
    <script>
        Vue.component('my-component',{
            template:'<button v-model>+1</button>',
            data:function(){
                return{
                    counter:0
                }
            },
            methods:{
                handleClick:function(){
                    this.counter++;
                    this.$emit('input',this.counter);
                }
            }
        });
        var app = new Vue({
            el:'#app',
            data:{
                total:0
            }
        })
    </script>
</body>
</html>